I don't know what you mean when talking about Mini-tamiya plug. The plug used in 1/18 RC cars (Mini-Z and similar) seems quite weak for constant high current usage. 20W @12V means something like ~1.8A which is relatively large current for mini plug. In my current application, where step up SMPS is used, battery currents are even higher.
1/18 RC car mini plug is like this http://www.hobbypeople.net/gallery/233125.asp
Tamiya to mini plug adapter http://www.hobbypeople.net/gallery/255072.asp
I like those tamiya plugs since they are easy to operate and are polarity safe. There is also locking, so they keep attached during ride.
Kirjanmerkit